Thank you for contacting Octopus Support and great question on custom banners/notifications in Octopus. I can see you sent us an email for this issue so I have responded to that ticket but for other users who have a similar question I am posting up my response to that email below:
Unfortunately, that functionality is not available at the moment but you are welcome to post this up on our Submit an Idea’ page on our Octopus Roadmap (its a button on the top right of the page) and our engineers will be able to see your suggestion and see if it is something they could implement. I do not think this would be a high priority for our engineers to look at though, whilst I do agree it is a good idea! I know that might not be the news you wanted to hear but I did want to ensure we were honest with you.
To that end, I have some suggestions for you to look into to see if one would be a good workaround:
First, we have a feature called manual intervention and approvals, you could use this step at the start of your projects to show the warning message to any user who deploys that project, they would need to approve it before the project started to deploy which would mean they would have actually to read it. The only thing to note here would be if you have automatic release creation setup as it would do the release creation but would not auto-deploy it until the manual intervention step was approved, so something to be aware of there.
You could also use a prompted variable and in there you could choose a multi-line text box for your warning message and have the user enter something like ‘I understand’, the deployment will not kick off until that variable was filled in with ‘I understand’ which also means your users would read the warning message before deploying. The automatic release creation issue I mentioned above would also be applicable here too, you could not deploy this project until a value for that variable was entered so it would stop any auto-deployments.